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- /*
- * DoRayMe - a quick and dirty Raytracer
- * Cylinder implementation
- *
- * Created by Manoël Trapier
- * Copyright (c) 2020 986-Studio.
- *
- */
- #include <tuple.h>
- #include <ray.h>
- #include <shape.h>
- #include <cylinder.h>
- #include <math_helper.h>
- bool Cylinder::checkCap(Ray r, double t)
- {
- /* Helping function to reduce duplication.
- * Checks to see if the intersection ot t is within a radius
- * of 1 (the radius of our cylinder from the y axis
- */
- double x = r.origin.x + t * r.direction.x;
- double z = r.origin.z + t * r.direction.z;
- return (x * x + z * z) <= 1;
- }
- void Cylinder::intersectCaps(Ray r, Intersect &xs)
- {
- /* Caps only matter if the cylinder is closed, and might possibly be
- * intersected by the ray
- */
- if ((this->isClosed) && (fabs(r.direction.y) > getEpsilon()))
- {
- double t;
- /* Check for an intersection with the lower end cap by intersecting
- * the ray with the plan at y = this->minCap
- */
- t = (this->minCap - r.origin.y) / r.direction.y;
- if (this->checkCap(r, t))
- {
- xs.add(Intersection(t, this));
- }
- /* Check for an intersection with the upper end cap by intersecting
- * the ray with the plan at y = this->maxCap
- */
- t = (this->maxCap - r.origin.y) / r.direction.y;
- if (this->checkCap(r, t))
- {
- xs.add(Intersection(t, this));
- }
- }
- }
- void Cylinder::localIntersect(Ray r, Intersect &xs)
- {
- double A = r.direction.x * r.direction.x + r.direction.z * r.direction.z;
- /* Ray is parallel to the Y axis */
- if (A >= getEpsilon())
- {
- double B = 2 * r.origin.x * r.direction.x +
- 2 * r.origin.z * r.direction.z;
- double C = r.origin.x * r.origin.x + r.origin.z * r.origin.z - 1;
- double disc = B * B - 4 * A * C;
- if (disc >= 0)
- {
- double t0 = (-B - sqrt(disc)) / (2 * A);
- double t1 = (-B + sqrt(disc)) / (2 * A);
- double y0 = r.origin.y + t0 * r.direction.y;
- if ((this->minCap < y0) && (y0 < this->maxCap))
- {
- xs.add(Intersection(t0, this));
- }
- double y1 = r.origin.y + t1 * r.direction.y;
- if ((this->minCap < y1) && (y1 < this->maxCap))
- {
- xs.add(Intersection(t1, this));
- }
- }
- }
- this->intersectCaps(r, xs);
- }
- Tuple Cylinder::localNormalAt(Tuple point, Intersection *hit)
- {
- /* Compute the square of the distance from the Y axis */
- double dist = point.x * point.x + point.z * point.z;
- if ((dist < 1) && (point.y >= (this->maxCap - getEpsilon())))
- {
- return Vector(0, 1, 0);
- }
- if ((dist < 1) && (point.y <= this->minCap + getEpsilon()))
- {
- return Vector(0, -1, 0);
- }
- return Vector(point.x, 0, point.z);
- }
- BoundingBox Cylinder::getLocalBounds()
- {
- BoundingBox ret;
- ret | Point(-1, this->minCap, -1);
- ret | Point(1, this->maxCap, 1);
- return ret;
- }
- void Cylinder::dumpMe(FILE *fp)
- {
- fprintf(fp, "\"Type\": \"Cylinder\",\n");
- Tuple t = this->transformMatrix * Point(0, 0, 0);
- fprintf(fp, "\"pseudocenter\": { \"x\": %f, \"y\": %f, \"z\": %f}, \n",
- t.x, t.y, t.z);
- t = this->transformMatrix * Point(0, this->minCap, 0);
- fprintf(fp, "\"min\": %f, \n", t.y);
- t = this->transformMatrix * Point(1, this->maxCap, 1);
- fprintf(fp, "\"max\": %f, \n", t.y);
- Shape::dumpMe(fp);
- }
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